1. Field
Aspects of embodiments according to the present invention relate to an emission control line driver and an organic light emitting display using the same.
2. Description of the Related Art
Recently, various flat panel displays (FPDs) with reduced weight and volume as compared to cathode ray tube (CRT) displays have been developed. The FPDs include a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), and an organic light emitting display.
Among the FPDs, the organic light emitting display displays an image using organic light emitting diodes (OLEDs) that generate light by re-combination of electrons and holes. The organic light emitting display has a fast response speed and is driven with low power consumption. A typical organic light emitting display supplies current corresponding to data signals to the OLEDs by using transistors formed in pixels so that light is emitted by the OLEDs.
The typical organic light emitting display includes a data driver for supplying the data signals to data lines, a scan driver for sequentially supplying scan signals to scan lines, an emission control line driver for supplying emission control signals to emission control lines, and a display unit including a plurality of pixels coupled to the data lines, the scan lines, and the emission control lines.
The pixels included in the display unit are selected, when the scan signals are supplied to the scan lines, to receive the data signals from the data lines. The pixels that receive the data signals generate light with brightness (e.g., predetermined brightness) corresponding to the data signals and display a predetermined image. Here, the emission times of the pixels are controlled by the emission control signals that are supplied from the emission control lines. In general, the emission control signals are supplied to overlap the scan signals that are supplied to one scan line or two scan lines to set the pixels, to which the data signals are supplied, in a non-emission state.
Therefore, the emission control line driver includes stages coupled to the emission control lines. The stages receive at least four clock signals and output high or low voltages to output lines.
However, since the stages included in the typical emission control line driver are driven by at least four clock signals, a large number of transistors are included. Therefore, manufacturing cost increases and it is difficult to secure the reliability of driving. In addition, when the emission control line driver is formed of a PMOS transistor, a low level output is unstable.
To be specific, when a low signal is supplied to an emission control line, the gate electrode of the transistor that outputs the low signal is maintained at a lower voltage than the low signal. However, the voltage of the gate electrode of the transistor increases due to leakage current and the output of the low signal is unstable.